JPS6376709A - Width control method for tandem rolling mill - Google Patents

Abstract

PURPOSE:To eliminate width deviations by calculating a tension corrective amount for respective parts in the longitudinal direction and controlling tensions by repeatedly performing calculations so that a width deviation being not eliminated owing to a tension limit is sequentially and ultimately eliminated between succeeding upstream side stands. CONSTITUTION:A tension corrective amount arithmetic unit 4 predictively calculates a width deviation on the outlet side of a finishing mill from the target width based on respective measured values of width and temp. by a width gage PDW and a thermometer RDT. It is assumed that the predicted width deviation is eliminated between stands FM-FM+1 and a necessary tension between stands is calculated; if the tension exceeds a tension limit, another necessary tension to eliminate a residual deviation between upstream side stands FM-1-FM is calculated. By repeating those operations, respective tensions should be set at respective stands are calculated. A delay device 3 outputs a tension corrective amount to a looper controller 2 at the respective times when a segment which once reached an F1 stand reaches respective stands. A learning device 5 learns a temp. prediction model between stands and a width prediction model based on measured values by a thermometer FDT and a width gage FDW and gives the arithmetic unit 4 learned results.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (Industrial Field of Application) The present invention relates to tandem rolling mills such as iron hot strip mill finishing mills, and more particularly to tandem rolling mills such as finishing mills of iron hot strip mills. The present invention relates to a strip width control method for a tandem rolling mill that controls strip width.

(Prior Art) In a general hot strip mill, a heated slab is rolled in the order of a rough mill and a finishing mill, and the slab is adjusted to a predetermined thickness at the exit side of the finishing mill. However, regarding the strip width, the strip width in the longitudinal direction of the material at the exit side of the finishing mill is not necessarily constant due to temperature fluctuations such as skid marks caused by overheating in the heating furnace and width fluctuations at the exit side of the rough mill. The board width deviation from the standard value was 1".

Due to such sheet width deviation, in actual operation, the workpiece, 1-
A margin was provided to ensure that the width at the mill exit side did not fall below the target width over the entire length of the material in the longitudinal direction. In this case, if the plate width deviation is large, a large margin must be provided, which also causes a decrease in yield.

In recent years, improvements in yield direction and strip width accuracy have been sought, and various efforts have been made to control strip width, but there is no method to reduce strip width deviation at the exit side of a rolling mill in tandem rolling mills such as finishing mills. Another method is to change the tension between the stands. This takes advantage of the fact that when tension is applied between the stands, the width of the material between the stands shrinks.

Regarding such a method, conventionally, Japanese Patent Publication No. 1700/1982, Japanese Patent Publication No. 8547/1982, and Japanese Patent Application Laid-Open No. 57-58
Several control systems have been reported, such as in Japanese Patent Application Laid-open No. 910 and Japanese Patent Application Laid-Open No. 57-1'39414, but they are generally as follows.

First, based on the information on the strip width and temperature at the input side of the rolling mill, the deviation of the strip width from the target value at the exit side of the rolling mill is predicted when the material is rolled at the base tension level between the stands. This method calculates the tension required to eliminate this predicted plate width deviation between the stands and performs correction control on the base tension.

(Problems to be Solved by the Invention) Generally, it is said that it is preferable to change the inter-stand tension of a tandem rolling mill in a -1-flow stand group in order to avoid affecting the plate thickness. However, even if the strip width deviation from the target value P71F+ is removed on the exit side of the rolling mill in the conventional control system, it is not unique how much to remove between which stands.

In other words, the plate width deviation predicted at the exit side of the rolling mill may be removed by changing the tension between a single stand in the tandem rolling mill upstream stand group, or by changing the tension between all stands in the upstream stand group. It is also possible to remove it with nJ.

As described above, in the conventional method, it was not clear which stand should distribute the amount of strip width deviation removed at the exit side of the rolling mill. In addition, the amount of plate width deviation removed between stands is automatically determined in relation to the plate width control effect by changing the tension between stands.
There was no way to control it.

The present invention has been made to solve the problem described in item 1-1, and is a strip width control method for a tandem rolling mill that can effectively eliminate the strip width deviation from the predicted target width at the exit side of the rolling mill. The purpose is to provide.

[Structure of the invention]

(Means for Solving the Problems) The present invention predicts the width deviation at the exit side of the rolling mill when rolled based on the tension between stands based on the width and temperature of the material at the entrance side of the rolling mill. Assuming that this strip width deviation is to be removed between stands selected by taking into account the height difference in the temperature distribution between the stands, the necessary tension correction amount for each longitudinal part of the rolled material is calculated, and the correction tension exceeds the tension limit. In this case, the tension setting value between the stands is set as the limit value, and the tension correction is calculated by assuming that the plate width deviation that could not be removed is removed between the adjacent upstream stands, and the tension limit is used to remove the deviation that could not be removed completely. The present invention is characterized in that similar calculations are repeated until any deviation in board width that is not observed can be successively removed between the upstream stands, and the tension is controlled in accordance with the inter-stand tension correction amount obtained by these calculations.

(Function) Now, in order to understand this invention, let us consider the longitudinal temperature distribution of the monthly charge portion between the stands.

FIG. 2 shows the temperature of each portion in the longitudinal direction of the material located between the two stands of the Fi11 stand, which is a do-flow stand adjacent to the F stand.

In general, the temperature distribution in the longitudinal direction of the material between upstream stands occupies a large proportion of one cycle of temperature fluctuation due to the skid mark due to the rolling schedule, and it is assumed that point y in Figure 2 is the low temperature part of the skid mark. , the temperature difference ΔT1 between the peak value of the high temperature part and point X is usually 2
The temperature is between 5°C and 30°C. On the other hand, between the downstream stands, the proportion of the skid marks in one cycle of temperature fluctuation is small, and the height difference ΔT2 in the temperature in the longitudinal direction between the stands is very small.

Next, let's consider the tension applied between the stands and the amount of width reduction between the stands.

FIG. 3 shows the relationship between the tension between stands and the amount of width shrinkage when temperature is used as a parameter, and the higher the temperature of the key material, the greater the width shrinkage.

Therefore, like between the first flow stand of a tandem rolling mill,
In places where there is a large difference in temperature in the longitudinal direction of the material, even if the same inter-stand tension is applied, even if the tension is appropriate in the low temperature part, the amount of shrinkage in the high temperature part may be too large, causing width defects.

In this way, when controlling the board width by changing the tension between the stands, the tension setting for a specific part in the longitudinal direction between the stands has an adverse effect on the board width of other material parts between the same stands.

To avoid this problem, it is best to select as many downstream stands as possible, where there is little difference in temperature distribution between the stands, and control the board width using inter-stand tension. Since the tension force has a negative effect on the plate thickness, rolling 1. It is necessary to choose an intermediate stand distance determined by business conditions.

When performing plate width control using a tension gauge between the stands on the 1st stream side of the stands selected in this way, taking into consideration the height difference in the temperature distribution between the stands, as much as possible between the selected stands, It is better to eliminate plate width deviation.

This will be explained in more detail below using mathematical formulas.

It has been found through experiments that the width reduction amount ΔW between the stands can be expressed in the form of equation (1).

ΔW−f(W, σ, T) ・・・・・・・・・
- (1) However, W: plate width σ: tension between stands T: material temperature.

Furthermore, it was found through experiments that the width expansion md due to the reduction in the stand is given by equation (2).

d-g(r, Ωd) ・・・・・・・・・(2
) Tapping r: Reduction rate Ωd: Contact arc length.

As can be seen from equation (2), when the plate thickness on the exit side of the finishing mill is large, the rolling reduction is generally small, and therefore the amount of width is small.

In strip width control in the tandem rolling mill of the present invention, each portion (hereinafter referred to as a segment) divided in the longitudinal direction of the material is
Consider the tension settings for each stand. The length of this segment is determined in consideration of the rolling schedule and strip width control effect.

Now, if a certain segment on the entry side of the finishing mill is rolled with the set standard tension between each stand, then the width shrinkage ΔW0 at the exit side of the finishing mill can be calculated by using equation (1) to calculate the width shrinkage between all stands. is given as the sum of

That is, where: ΔW: 20 width reduction due to standard tension at l stand.

σ, :l stand ~ (i+1) stand Setting tension between cables N; Number of stands T: Material temperature It is.

Further, the width expansion Cd due to reduction in all stands is calculated as follows using equation (2).

- Σ g, (r, Ω,) ・・・・・・(
4) 1dl t=straightening, d, : widening amount r at l stand, : rolling reduction ratio Ω at l stand: contact arc length i at l stand.

Plate width change Δ required to change the segment width WRD at the entry side of the finishing mill to the target width WFD at the exit REP side.
Wl'M is REP ΔWFM=WMl) "I!11...
...(5).

Therefore, by correcting the inter-stand tension, the board width deviation a WSTD i to be removed in the group between the stands is ΔW −ΔW, H−ΔW 0 +d
・・・・・・ (G) TD becomes.

In the present invention, the board width deviation ΔWSTD is removed between the most downstream stands in the upstream stand group (hereinafter referred to as the M stand (M+1) stand). ~1 stand~l+1) The inter-stand tension σM required to make the board width deviation ΔWSTD zero between the stands alone can be obtained as in the equation (7) by solving the tension from the relationship in the equation (1).

σ −h (W, TM, ΔWsTD+ΔWM)M (7) It is sufficient if this tension value σM is equal to or less than the tension limit value σ8 that can be set between M stands (M+1) stand IM. As shown in Figure 4 (a), σM is], 1M σM is 1. If it is the same, M Standre (N4+1)
The tension between the IM stands is set to a limit value σM.

Then, the plate width deviation* difference ΔWM-1 that could not be completely removed between the M stands is calculated as the difference ΔWM-1 between the adjacent upstream stands (M-1
) is removed between stand and M stand. ΔWM-1 at this * time is ΔW book −ΔW +d−f (W, σ, T
) IM M-I PHM M (8).

(M-1) Between stand M and stand M, Figure 4 shows 0.
* The tension σM-1 required to reduce the sum of the amount ΔWM-1 and the above plate width deviation ΔWM-1 is determined from the relationship of equation (1). That is, σ ″h (W・TM−1・M−I M−1 0* ΔW +Δw,, > (9) Similar procedure,
Repeat this process until the plate width deviation becomes zero, and then determine the required tension in order toward the upstream side.

One way to select an M stand is as follows.

(1. Measure the skid mark interval LSKI' for the material length ΩIIAR on the L entry side). SKD is the number of skid marks.

Next, It l-: Entrance side plate thickness hBAI? From each stand thickness target h1 when setting the finishing mill to i stand (i+1
)Skid mark period length Ω5K corresponding to between stands
Find Di.

Here, the skid mark period length gS of the distance between stands
Considering the ratio to KDi, among the stands with ΩSKD i , the smallest stand of i, that is, the stand on the most upstream side, is selected as the M stand. Tatami, βSTD
i is the distance between i stands (i+1) stands, and ε is a constant.

In this way, by handling the ratio of the distance between stands to the skid mark period length, it is also possible to change the M stand for each rolling material.

(Example) FIG. 1 is a block diagram showing a +14 configuration of an apparatus u implementing the present invention together with a rolling system to which the invention is applied.

In the same figure, pulse generators PG-PGN for detecting rolling roll rotational speeds are connected to the finishing mill stand groups F1 to FN, respectively, and between the finishing mill stand groups F1 to FN, pulse generators PG to PGN are connected to finishing mill stand groups F1 to FN. , louvers LP-LPN, which are inter-stand tension generators, respectively.
are provided, and the looper control device 2 controls these.

-No.j, the exit side of the rough rolling mill (not shown), ie, fl:
On the entry side of the I-mill stand group, a width: 1 RDW for measuring the plate width of the rolled material 1 and a temperature = IRDT for measuring the temperature are provided, and each measurement signal is used as a tension correction amount calculation device for calculating tension correction 2. 4 is input. Also, on the exit side of the finishing mill stand group, there is a width gauge FDW for determining the width of the rolled material 1 Cj.
A thermometer FDT is installed to measure the temperature.
The l constant signal is manually input to a learning device 5 which performs learning of an inter-stand temperature prediction model and a board width prediction model. Then, the predicted value of the learning device 5 is input manually to the tension correction Q calculation device 4.

Next, a delay device 3 is connected to the tension correction amount calculation device 4 to delay the output time so that the calculated tension correction value is applied to each looper control device 2 at an appropriate time.

Hereinafter, the operation will be described assuming that the FM stand located in the middle of the residential mill stand groups F1 to FN is selected as the stand that performs board width control.

First, t■ Width provided on the exit side of the rolling mill: JRDW and F
A degree: 1RDT measures the plate width and lH degree of the rolled material 1 for each segment in the longitudinal direction of the material.

Based on the measured sheet width and temperature, the tension correction amount calculating device 4 calculates the target value at the finish 1-mill exit side for the segment that has reached the F1 stand, assuming that it has passed between the stands at the set standard tension. The plate width deviation from 1 is predicted using equation (6). At this time, the inter-stand material temperature used is estimated from the temperature measured by the thermometer RDT using a well-known temperature drop model.

The plate width deviation predicted in this way is first removed only between the FM stand and the FM+1 stand, and the necessary inter-stand tension is calculated using the above equation (7). If the calculated tension exceeds the tension limit, apply (8) above between the upstream FM-1 stand and the FM stand.
Calculate the tension required to remove the amount corresponding to the formula.

After the tension to be set between each stand is calculated by sequentially repeating these operations, the difference from the reference tension is stored as the tension to be corrected.

Next, the delay device 3 sets the tension correction i to 1 at the time when the segment that has reached the Fl stand has reached between each stand.
'F,2 is output to the looper control device 2.

The arrival time of the segment between each stand is determined by the pulse generator P C-P C attached to the rolling roll.
, is determined based on the detected value of .

-h, the learning device 5 learns the inter-stand temperature prediction model and the plate width prediction model based on the thermometer FDT and width meter FDW provided on the exit side of the finishing mill, and sends the learning device 5 to the tension correction amount calculation device 4. give. Therefore, the accuracy of plate width control can be improved.

FIG. 5 is an explanatory diagram of the operation when the above-mentioned sheet width control is implemented, and the sheet width (abbreviated as rough width) detected by the width gauge RDW is constant for the sake of simplicity. Assume that there is. However, the material temperature detected by the thermometer RDT (
(abbreviated as crude temperature) fluctuates as shown by skid marks. If the control as in the above embodiment is not performed in this state, the width of the plate at the exit side of the finishing mill (abbreviated as the top exit width) detected by width: IFDW will fluctuate as shown by the broken line. .

In this embodiment, in order to eliminate this plate width variation, first M
Standle (M+1) The plate width deviation of the inter-stand tension σ8 cannot be completely removed between these stands, so the upstream side (
M-1) Correct the tension σM-1 between the stands and the M stand to remove the plate width deviation.

Therefore, the strip width at the exit side of the finishing mill remains constant without being affected by skid marks.

〔Effect of the invention〕

As is clear from the above explanation, the strip width deviation is removed between the stands selected by taking into account the height difference in the abrasive temperature distribution between the stands, and the strip width deviation that cannot be removed by the tension limit is sequentially removed. Since the removal method is adopted at the upstream stand, correcting the tension on the specific part of the stand opening does not adversely affect other parts, and it is possible to perform good board width control.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an apparatus for carrying out the present invention together with a rolling system to which the present invention is applied, and FIG. 2 is a block diagram showing the position between stands and the rolled material
3, 4(a) and 4(b) are explanatory diagrams showing the relationship between the tension between the stands and the width reduction 2, in order to explain the present invention in detail. The diagram shown in FIG. 5 is an explanatory diagram showing the relationship between the longitudinal position of the rolled material, the width of the material, the temperature, and the tension, in order to explain the operation of one embodiment of the present invention. -FN...Finishing mill stand, PG1~PC...
・Pulse generator, LP - LPN... Looper, RDW, FDW... Width meter, RDT, FDT... Temperature r
U meter, 2... Louver control device, 3... Delay device, 4... Tension correction amount calculation device, 5... Learning device. - Staside value 1 Stand between one stand L Figure 2 Figure 3 Figure M stand ~ M

Claims (1)

[Claims] In a strip width control method for a tandem rolling mill that controls the strip width by controlling the tension between the stands, rolling according to the inter-stand tension standard based on the strip width and temperature of the material at the entrance side of the rolling mill. Assuming that the strip width deviation at the exit side is predicted and this strip width deviation is removed between stands selected by taking into account the height difference in the temperature distribution between the stands, the amount of tension correction required for each longitudinal section of the rolled material is calculated. is calculated, and if the corrected tension exceeds the tension limit, the tension setting value between the stands is set as the tension limit value, and the tension is corrected in the same way, assuming that the board width deviation that could not be removed is removed between the adjacent upstream stands. The same calculations are repeated until the plate width deviation that cannot be removed by the tension limit can be removed sequentially between the upstream stands, and the tension is controlled according to the inter-stand tension correction amount obtained by these calculations. Features a strip width control method for tandem rolling mills.